and lastly, there is the issue of the size of their nukes. there is no indication that the north koreans have created a nuclear weapon small enough to ride on top of these rockets that. is a huge challenge that takes a lot of work. they are not there yet. that's one of the reasons many intelligence analysts are being looking at these very sharp words, wolf, as secretary panetta suggested, you have to be serious about it but it's probably just an empty threat at this point. >> good explanation, tom. thank you. >>> and joining us now, the abc news global affair's anchor, christiane amanpour. how credible are these threats coming out of north korea? >> they are credible as threats and they hope to make these a deterrent but when it comes to could they actually and do they intend to launch anything against the united states? the consensus is no. not only do they not have the ability to invade, but they don't have the ability on long-range missiles and they are not considered to have the ability to put a nuclear warhead on a missile. the problem,